The present invention is directed to an optical device for observing the ends of optical waveguides which are being adjusted relative to one another for splicing purposes, in particular, for observing the ends of monomode optical waveguides through a microscope.
An optical device for observing the ends of optical waveguides, which are being spliced, is disclosed in U.S. patent application Ser. No. 558,878, which claims priority from German application No. P 32 45 229. With the aid of this optical device or installation, which is integrated into a thermal optical waveguide fusing or splicing apparatus, the alignment of the ends of the waveguides, which are to be fused together in a longitudinal direction, can be observed. Since the optical waveguides are centered in aligned V-shaped grooves, the alignment in the transverse direction is not necessary. The optical installation itself consists of an illumination device, a lens, which images the splicing location via two deflection mirrors, which are arranged in the optical path, on a ground glass screen and of a magnifier through which the image produced on the ground glass screen is viewed and enlarged once again. Through the optical device constructed in this fashion, it is then possible in addition to the alignment of the optical waveguides in a longitudinal direction to also monitor the fusing operation in a comprehensive manner from the beginning to the end.
In addition to an alignment of the ends of the optical waveguides in a longitudinal direction, which ends are to be spliced to one another, an alignment through rotation of the optical waveguides and an alignment in two transverse directions which are perpendicular to one another can be necessary. For example, optical waveguides with fracture surfaces which extend obliquely relative to the respective longitudinal axis must be aligned to as small as possible gap or slit spacing by rotating one of the optical waveguides about its longitudinal axis. Otherwise, a relatively high splicing attenuation will result after splicing if the two end faces have not been rotated to provide the smallest gap therebetween. In the case of monomode optical waveguides whose cores exhibit very small dimensions in the order of magnitude of approximately 10 um and are eccentrically positioned in the waveguide, a possible considerable splicing attenuation will result. Therefore, in the case of monomode optical waveguides of this type, a rotation of the optical waveguide about its longitudinal axis and through an adjustment of the two transverse directions which are perpendicular to one another, an adjustment must be attained in which the core region of the optical waveguides are in precise alignment. Accordingly, an observation of this adjustment operation must proceed from two transverse directions which are perpendicular to one another. However, the optical installation proposed in the above-mentioned patent application is not suited for this purpose since it permits only an observation of the splicing location from one transverse direction.